1. Field of the Invention
The invention relates to a power electronics unit, in particular for a control device in a motor vehicle, with a planar ceramic substrate, on one side of which conductor tracks are provided using the thick-film technique for electrically connecting electrical power components of a circuit that are likewise arranged on the ceramic substrate and which is brazed by its other side onto a metal support element serving as a heat spreader, the support element being connected in a thermally conducting manner to a thermally conducting housing component of a housing accommodating the support element.
2. Description of the Prior Art
With power electronics units there is the problem that the electrical power components generate heat, which has to be removed. For this purpose, it is known to form the support element as a planar ceramic substrate, on which conductor tracks are provided using a thick-film technique, and the electrical power components and any control components there may be are connected to the conductor tracks by soft soldering. The ceramic substrate is brazed to a metal support element, which serves as a heat spreader and is connected to a thermally conducting housing component by means of an adhesive.
On account of the different coefficients of expansion of the support element and the ceramic substrate, these components deform to differing degrees, which can have the effect during cooling after brazing that the ceramic substrate is damaged and later the soft-solder connections between the conductor tracks and the electrical power components are possibly also damaged.